On 6/28/20 10:55 PM, Song Liu wrote:
> The new test is similar to other bpf_iter tests. It dumps all
> /proc/<pid>/stack to a seq_file. Here is some example output:
>
> pid: 2873 num_entries: 3
> [<0>] worker_thread+0xc6/0x380
> [<0>] kthread+0x135/0x150
> [<0>] ret_from_fork+0x22/0x30
>
> pid: 2874 num_entries: 9
> [<0>] __bpf_get_stack+0x15e/0x250
> [<0>] bpf_prog_22a400774977bb30_dump_task_stack+0x4a/0xb3c
> [<0>] bpf_iter_run_prog+0x81/0x170
> [<0>] __task_seq_show+0x58/0x80
> [<0>] bpf_seq_read+0x1c3/0x3b0
> [<0>] vfs_read+0x9e/0x170
> [<0>] ksys_read+0xa7/0xe0
> [<0>] do_syscall_64+0x4c/0xa0
> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Note: To print the output, it is necessary to modify the selftest.
I do not know what this sentence means. It seems confusing
and probably not needed.
>
> Signed-off-by: Song Liu <[email protected]>
Acked-by: Yonghong Song <[email protected]>
> ---
> .../selftests/bpf/prog_tests/bpf_iter.c | 17 +++++++++
> .../selftests/bpf/progs/bpf_iter_task_stack.c | 37 +++++++++++++++++++
> 2 files changed, 54 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> index 1e2e0fced6e81..fed42755416db 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> @@ -5,6 +5,7 @@
> #include "bpf_iter_netlink.skel.h"
> #include "bpf_iter_bpf_map.skel.h"
> #include "bpf_iter_task.skel.h"
> +#include "bpf_iter_task_stack.skel.h"
> #include "bpf_iter_task_file.skel.h"
> #include "bpf_iter_tcp4.skel.h"
> #include "bpf_iter_tcp6.skel.h"
> @@ -110,6 +111,20 @@ static void test_task(void)
> bpf_iter_task__destroy(skel);
> }
>
> +static void test_task_stack(void)
> +{
> + struct bpf_iter_task_stack *skel;
> +
> + skel = bpf_iter_task_stack__open_and_load();
> + if (CHECK(!skel, "bpf_iter_task_stack__open_and_load",
> + "skeleton open_and_load failed\n"))
> + return;
> +
> + do_dummy_read(skel->progs.dump_task_stack);
> +
> + bpf_iter_task_stack__destroy(skel);
> +}
> +
> static void test_task_file(void)
> {
> struct bpf_iter_task_file *skel;
> @@ -452,6 +467,8 @@ void test_bpf_iter(void)
> test_bpf_map();
> if (test__start_subtest("task"))
> test_task();
> + if (test__start_subtest("task_stack"))
> + test_task_stack();
> if (test__start_subtest("task_file"))
> test_task_file();
> if (test__start_subtest("tcp4"))
> diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
> new file mode 100644
> index 0000000000000..e40d32a2ed93d
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_stack.c
> @@ -0,0 +1,37 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Facebook */
> +#include "bpf_iter.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +#define MAX_STACK_TRACE_DEPTH 64
> +unsigned long entries[MAX_STACK_TRACE_DEPTH];
> +#define SIZE_OF_ULONG (sizeof(unsigned long))
> +
> +SEC("iter/task")
> +int dump_task_stack(struct bpf_iter__task *ctx)
> +{
> + struct seq_file *seq = ctx->meta->seq;
> + struct task_struct *task = ctx->task;
> + long i, retlen;
> +
> + if (task == (void *)0)
> + return 0;
> +
> + retlen = bpf_get_task_stack(task, entries,
> + MAX_STACK_TRACE_DEPTH * SIZE_OF_ULONG, 0);
> + if (retlen < 0)
> + return 0;
> +
> + BPF_SEQ_PRINTF(seq, "pid: %8u num_entries: %8u\n", task->pid,
> + retlen / SIZE_OF_ULONG);
> + for (i = 0; i < MAX_STACK_TRACE_DEPTH; i++) {
> + if (retlen > i * SIZE_OF_ULONG)
> + BPF_SEQ_PRINTF(seq, "[<0>] %pB\n", (void *)entries[i]);
> + }
> + BPF_SEQ_PRINTF(seq, "\n");
> +
> + return 0;
> +}
>
> On Jun 29, 2020, at 8:06 AM, Yonghong Song <[email protected]> wrote:
>
>
>
> On 6/28/20 10:55 PM, Song Liu wrote:
>> The new test is similar to other bpf_iter tests. It dumps all
>> /proc/<pid>/stack to a seq_file. Here is some example output:
>> pid: 2873 num_entries: 3
>> [<0>] worker_thread+0xc6/0x380
>> [<0>] kthread+0x135/0x150
>> [<0>] ret_from_fork+0x22/0x30
>> pid: 2874 num_entries: 9
>> [<0>] __bpf_get_stack+0x15e/0x250
>> [<0>] bpf_prog_22a400774977bb30_dump_task_stack+0x4a/0xb3c
>> [<0>] bpf_iter_run_prog+0x81/0x170
>> [<0>] __task_seq_show+0x58/0x80
>> [<0>] bpf_seq_read+0x1c3/0x3b0
>> [<0>] vfs_read+0x9e/0x170
>> [<0>] ksys_read+0xa7/0xe0
>> [<0>] do_syscall_64+0x4c/0xa0
>> [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> Note: To print the output, it is necessary to modify the selftest.
>
> I do not know what this sentence means. It seems confusing
> and probably not needed.
It means current do_dummy_read() doesn't check/print the contents of the
seq_file:
/* not check contents, but ensure read() ends without error */
while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
;
>
>> Signed-off-by: Song Liu <[email protected]>
>
> Acked-by: Yonghong Song <[email protected]>
Thanks!
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